CNT-SVX05A-EN
71
Troubleshooting
Questionable unit operation
Table 58 — Fan outputs do not energize
Table 59 — Valves stay open
Probable cause
Explanation
Power up control wait
When power up control wait is enabled (non-zero time), the controller
remains off until one of two conditions occurs:
The controller exits power up control wait when it
receives communicated information.
The controller exits power up control wait when the power up
control wait time expires.
Unoccupied operation
When the controller is in the unoccupied mode, the fan is cycled between
high speed and off with capacity to maintain zone temperature control.
Fan mode off
When a local fan mode switch (provided on the Trane zone sensor)
determines the fan operation, the off position controls the unit off.
Requested mode off
You can communicate a desired operating mode (such as off, heat, and cool)
to the controller. When off is communicated to the controller, the unit controls
the fan off. There is no heating or cooling.
Diagnostic present
Specific diagnostics affect fan operation. For more information,
see the
Diagnostics
section.
No power to the
controller
If the controller does not have power, the unit fan does not operate.
For the controller to operate normally, it must have an input voltage of 24VAC.
When the green LED is off continuously, the controller does not have
sufficient power or has failed.
Unit configuration
The controller must be properly configured based on the actual installed end
devices and application. When the unit configuration does not match the
actual end devices, the fan may not work correctly.
Manual output test
The controller includes a manual output test sequence you can use to verify
output operation and associated output wiring. However, based on the
current step in the test sequence, the unit fan may not be on.
Refer to the
Manual output test
section.
Unit wiring
The wiring between the controller outputs and the fan relays and contacts
must be present and correct for normal fan operation.
Probable cause
Explanation
Normal operation
The controller opens and closes the valves to meet the unit
capacity requirements.
Manual output test
The controller includes a manual output test sequence you can use to verify
output operation and associated output wiring. However, based on the
current step in the test sequence, the valve(s) may be open.
Refer to the
Manual output test
section.
Freeze avoidance
When the controller is in the unoccupied mode with no demand for capacity
(0%) and the outdoor air temperature is below the freeze avoidance setpoint,
the controller opens the water valves (100%) and the face and bypass damper
to prevent coil freezing.
Diagnostic present
Specific diagnostics affect valve operation. For more information,
see the
Diagnostics
section.
No power to the
controller
If the controller does not have power, a normally open valve remains open.
For the controller or valve to operate normally, it must have an input voltage
of 24VAC. When the green LED is off continuously, the controller does not
have sufficient power or has failed.
No power to the valves If the valve does not have power, a normally open valve remains open.
The valves are powered separately from the controller's output signal.
If the valves do not have 24VAC, the controller cannot operate the valves.
Unit configuration
The controller must be properly configured based on the actual installed end
devices and application. When the unit configuration does not match the
actual end devices, the valves may not work correctly.
Unit wiring
The wiring between the controller outputs and the valve(s) must be
present and correct for normal valve operation.
